Petrogenesis, Geochronology, and Tectonic Significance of Granitoids In

Journal of Asian Earth Sciences 79 (2014) 792–809

Contents lists available at SciVerse ScienceDirect

Journal of Asian Earth Sciences

journal homepage: www.elsevier.com/locate/jseaes

Petrogenesis, geochronology, and tectonic signiﬁcance of granitoids in the Tongshan intrusion, Anhui Province, Middle–Lower Yangtze River Valley, eastern China ⇑ Zhi-Yu Zhang a, , Yang-Song Du a, Chuan-Yao Teng a, Jing Zhang a, Zhen-Shan Pang b a State Key Laboratory of Geological Process and Mineral Resources, China University of Geosciences, Beijing 100083, People’s Republic of China b Development and Research Center of China Geological Survey, Beijing 100037, People’s Republic of China article info abstract

Article history: The Tongshan copper deposit in Anhui Province is a typical mid-sized skarn and porphyry type deposit in Available online 25 April 2013 the Anqing–Guichi district along the Middle–Lower Yangtze River Valley, eastern China. The Tongshan intrusion is closely related to this mineralization. The intrusion mainly comprises rocks that are quartz Keywords: diorite porphyry, quartz monzonite porphyry, and granodiorite porphyry. Plagioclase in these rocks is Tongshan intrusion mostly andesine (An = 31.0–42.9), along with minor oligoclase. Biotite is magnesium-rich [Mg/ Petrogenesis (Mg + Fe) = 0.52–0.67] and aluminum-poor (Al2O3 = 12.32–14.09 wt.%), and can be classiﬁed as magne- SHRIMP zircon U–Pb dating sio-biotite. Hornblende is TiO -poor (<1.96 wt.%) and magnesium-rich [Mg/(Mg + Fe) > 0.60], and is Mineral chemistry 2 magnesio-hornblende or edenite. The SHRIMP zircon U–Pb age of the quartz monzonite porphyry is Geochemistry The Middle–Lower Yangtze River Valley 145.1 ± 1.2 Ma, which corresponds to the middle Yanshanian period. Whole-rock geochemical results show that the rocks are silica-rich (SiO2 = 60.23–66.23 wt.%) and alkali-rich (K2O+Na2O = 4.97– 8.72 wt.%), and low in calcium (CaO = 2.61–5.66 wt.%). Trace element results show enrichments in large ion lithophile element (e.g., K, Rb, and Ba) and depletions in some high ﬁeld strength elements (e.g., Nb, Ta, P, and Ti). The total rare earth element (REE) content of the rocks is low (RREE < 200 lg/g), and they

exhibit light REE enrichment [(La/Yb)N > 10] and small positive Eu anomalies (average dEu = 1.16). These mineralogical, geochronological, and geochemical results show that the intrusion has a mixed crust– mantle source. The Tongshan intrusion was formed by multiple emplacements of crustally contaminated basaltic magma generated by varying degrees of partial melting of enriched lithospheric mantle and lower crust. Hornblende thermobarometry yielded magmatic crystallization temperatures of 652– 788 °C and an average crystallization pressure of 1.4 kbar, which corresponds to a depth of approx. 4.7 km. Biotite thermobarometry yielded similar temperatures and lower pressures of 735–775 °C and 0.6 kbar (depth 2.1 km), respectively. The parental magma had a high oxygen fugacity and was produced in a volcanic arc setting related to subduction of the paleo-Paciﬁc plate. Ó 2013 Elsevier Ltd. All rights reserved.

1. Introduction ies of Mesozoic magmatic rocks in the MLYRB have yielded a number of important insights into their origins and those of associated The Middle-Lower Yangtze River Valley metallogenic belt ore deposits. It is currently considered that this metallogenic belt (MLYRB) is a region of large-scale magmatic activity and metallo- comprises multiple distinctive ore clusters or mining districts genesis in eastern China (Fig. 1a) (Pan and Dong, 1999). In this (Fig. 1). A focus of ongoing research is the use of geochronology belt, Mesozoic magmatic rocks and their related copper, gold, and geochemistry to constrain the timing, petrogenesis, and tec- and iron ores (Ma and Shan, 1997) have been the focus of numer- tonic setting of magmatism. A large amount of zircon dating has ous studies (Zhou et al., 2003; Mei et al., 2005; Ding et al., 2006; been conducted on magmatic rocks of the different districts, Du et al., 2007), with a particular focus on the ore-forming ﬂuids including Edong (southeastern Hubei province) (Xie et al., 2006, and ore genesis (Zeng et al., 2004; Jiang et al., 2008; Lu et al., 2011; Xie et al., 2012a; Li et al., 2009a), Jiurui (Jiujiang–Ruichang) 2008; Mao et al., 2009) and geodynamics (Li, 2000; Chen et al., (Ding et al., 2005; Li and Jiang, 2009; Xu et al., 2012), the Anqing 2001, 2004, 2005; Zhang et al., 2006; Mao et al., 2011). These stud- section in Anqing–Guichi (Chen et al., 1991; Zhang et al., 2008; Liu et al., 2009), Luzong (Lujiang–Zongyang) (Zhou et al., 2007; Zeng et al., 2010; Xue et al., 2012), Tongling (Wang et al., 2004a; Yang ⇑ Corresponding author. Tel.: +86 13811712407. et al., 2008, 2011; Cao et al., 2009), and Ningwu (Nanjing–Wuhu) E-mail address: [email protected] (Z.-Y. Zhang). (Yan et al., 2009a,b; Hu and Jiang, 2010). However, compared with

Fig. 1. (a) Simpliﬁed structural map of China. (b) Distribution of magmatic rocks and ore clusters (districts) in the Middle and Lower Yangtze River metallogenic belt (modiﬁed from Zhai et al., 1992; Tang et al., 1998; Du et al., 2003; Mao et al., 2009, 2011). TLF = Tancheng–Lujiang Fault; XGF = Xiangfan–Guangji Fault; YCF = Yangxing– Changzhou Fault.

the aforementioned districts, research on the Guichi section in the area, which in turn enhances our understanding of the dynamics Anqing–Guichi area has been limited, particularly in terms of geo- of Mesozoic magmatism in the MLYRB. chronology and magma petrogenesis. The absence of such data hinders development of an in-depth understanding of the occur- 2. Geological background rence and petrogenesis of Mesozoic magmatism in the Anqing– Guichi district and the MLYRB as a whole. The Tongshan intrusion is located in Tongshan town (Chizhou, Tongshan is a typical ore-bearing intrusion in the Guichi section Anhui Province), and is typical of many ore-bearing plutons in of the Anqing–Guichi district. A limited amount of research on the the Anqing–Guichi district of the MLYRB (Fig. 2a). The intrusion petrology, and elemental and isotopic geochemistry, has been car- is structurally located at the bend in the Tongshan arc-shaped ried out on the Tongshan intrusion (Li and Shao, 1994; Yu and structure in the southeastern ﬂank of the Mushan anticline at the Yuan, 1999a,b; Lü, 2000; Yu, 2001; Zhou, 2003). In terms of mag- northern margin of the Yangtze plate and in the middle of the fold matic evolution, it is considered that the Tongshan intrusion repre- belt of the Lower Yangtze syneclise. Strata in the area of the Tong- sents a calc-alkaline rock series (Lü, 2000). Magmatic evolution shan ore deposit mainly comprise sedimentary rocks of the Upper resulted in ore-forming elements being enriched in magmatic- Silurian Maoshan Formation and Lower Triassic Biandanshan For- hydrothermal systems, which were favorable for the formation of mation (Fig. 2), which were deposited in the neritic–littoral facies a variety of ore types (Yu and Yuan, 1999b). These previous studies (Wang, 2003). Occurrences of the magmatic rocks are controlled by tentatively established element ratio indicators that could be used concealed east–west- and northwest-trending faults, and the shal- to distinguish different mineralization types and ore body depths low sub-surface structure is northeast-trending (Lü, 2000). At (Li and Shao, 1994). The Tongshan copper deposit is a stratabound depth, irregular northeast-trending stocks occur and also crop skarn deposit that includes a lesser amount of porphyry-type min- out at the surface over an area of approx. 2 km2. The surrounding eralization (Yu, 2001). The ore-forming elements were derived country rocks are Silurian–Devonian clastic sediments and Carbon- from multiple sources. The granodiorite porphyry, interlayer iferous–Permian carbonate rocks. In the contact zone, the rocks are detachment faults, and country rocks appear to have been the main mainly marble, dolomitic marble, hornfels, calcareous skarn, and factors controlling the sites of ore formation (Zhou, 2003). Despite magnesian skarn. Hydrothermal alteration is ubiquitous in the these previous studies, there have been no detailed mineralogical, Tongshan copper deposit and is characterized by siliciﬁcation, geochronological, and geochemical investigations of the Tongshan sericitization, biotitization, chloritization, carbonatization, potassic intrusion. Herein, we present a systematic mineralogical, precise alteration, and pyritization. SHRIMP zircon U–Pb geochronological, and geochemical study of The Tongshan intrusion mainly comprises rocks that are quartz the Tongshan intrusion. We use these data to constrain the timing, diorite, quartz monzonite porphyry, and granodiorite porphyry (Yu petrogenesis, and tectonic setting of magmatism in the Tongshan and Yuan, 1999b). The quartz diorite is in the center of the 794 Z.-Y. Zhang et al. / Journal of Asian Earth Sciences 79 (2014) 792–809

Fig. 2. Schematic geological map of the Tongshan copper ore deposit (a-modiﬁed from Sun et al., 2008; Shao et al., 2009). D3w = Upper Devonian Wutong Formation; C– P = Carboniferous–Permian; T = Triassic; S = Silurian.

intrusion, whereas the quartz monzonite porphyry and granodio- microcrystalline with a crystal size of <0.1 mm, which comprises rite porphyry form the border phases of the pluton. Granodiorite quartz (20–25%), K-feldspar (15%), and accessory minerals porphyry lithologies are most closely related to copper sulfide min- (1%) of magnetite, titanite, apatite, zircon, and allanite. In some eralization. The samples used in this study were collected from the samples, primary rock-forming minerals exhibit varying degrees open pit mine of the Qianshan ore block (Fig. 2b) and also taken of alteration, including chloritization of hornblende and biotite, from diamond drill core material. All of the samples were taken sericitization of plagioclase, and sulfidation reactions to form pyr- from the mid- to shallowly-crystallized phases of the intrusion. ite and chalcopyrite. We focused our geochemical studies on sam- The samples are principally quartz diorite porphyry, quartz mon- ples without obvious signs of alteration. zonite porphyry, and granodiorite porphyry. The quartz diorite porphyry has a porphyritic texture (Fig. 3a) with 80% phenocrysts. The phenocrysts are hornblende (12–15%), plagioclase 3. Analytical methods (63–65%), and local biotite (3%) and K-feldspar (2%). The matrix has a micro-poikilitic texture with a crystal size of 0.15–0.30 mm, Representative unaltered magmatic rocks were collected in the which comprises K-feldspar (7–10%), quartz (8–12%), and acces- field for petrographic study and determination of mineral chemis- sory minerals (<2%) of magnetite, apatite, zircon, and titanite. try. Zircon U–Pb dating was carried out on a quartz monzonite por- The quartz monzonite porphyry has a porphyritic texture phyry sample. Selected samples from the suite of collected rocks (Fig. 3b) with 55% phenocrysts. The phenocrysts are plagioclase were chosen for whole-rock geochemical analysis. (30–35%), biotite (13%), and hornblende (<5%). The matrix has a Major element mineral chemistry was determined at the State microcrystalline texture with a crystal size <0.05 mm, which com- Key Laboratory for Continental Tectonics and Dynamics, Institute prises K-feldspar (25–30%), quartz (18%), and accessory minerals of Geology, Chinese Academy of Geological Sciences, Beijing, China. (<2%) of apatite, magnetite, and zircon. Polysynthetic twins and A JXA-8100 electron microprobe was used for these measurements oscillatory zoning characterize the plagioclase. The matrix K-feld- and was operated at a voltage of 15 kV, beam current of 2 10–8 A, spar is fine-grained and anhedral, and occurs interstitially to euhe- and beam diameter of 5 lm. dral plagioclase phenocrysts. The granodiorite porphyry also has a Preparation of samples for zircon dating and whole-rock geo- porphyritic texture (Fig. 3c) with 60% phenocrysts. The pheno- chemistry was conducted in the Laboratory of the Institute of Geol- crysts are plagioclase (42–45%), hornblende (8–12%), biotite ogy and Mineral Resources, Langfang, Hebei Province, China. An (5%), K-feldspar (2%), and quartz (2%). The matrix is ultraclean ball mill was used to grind whole-rock samples to a Z.-Y. Zhang et al. / Journal of Asian Earth Sciences 79 (2014) 792–809 795

reflected light, and cathodoluminescence (CL) images were made to examine the internal structure of the zircon crystals and to guide the choice of analytical sites. Data processing was under- taken with the software Squid (Ludwig, 2001) and Isoplot (Ludwig, 2003). Measured 204Pb counts were used to correct for common Pb (Stacey and Kramers, 1975). The errors on the age data are quoted as ±1r and the final error on the weighted average 206Pb/238U age is given as ±2r. Whole-rock major and trace element analyses were made in the Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Peking University, Beijing, China. Major elements were determined by X-ray fluorescence spectrometry with an excitation current of 50 mA, excitation voltage of 50 kV, and a sensitivity of ±0.001 wt.%. Trace element analysis was conducted by inductively coupled plasma–mass spectrometry with an estimated relative precision and accuracy of ±10% (1r).

4. Results

4.1. Mineralogy and mineral chemistry

We focused on the characteristics and mineral chemistry of plagioclase, hornblende, and biotite in the quartz diorite porphyry, quartz monzonite porphyry, and granodiorite porphyry.

4.1.1. Plagioclase Plagioclase occurs as tabular, euhedral to subhedral phenocrysts, which often exhibit well-developed polysynthetic twinning (Fig. 3). Representative plagioclase major element analyses are given in Table 1. In the quartz diorite porphyry, plagioclase accounts for 79–81% of the phenocryst assemblage and has a crystal size of

0.4–0.8 mm. Plagioclase SiO2 contents vary from 60.10 to 62.28 wt.% (average = 61.40 wt.%), and An values mostly fall within the range of 31.0–36.9 (andesine), although a small number of plagioclase analyses are oligoclase (An = 28). In the quartz monzonite porphyry, plagioclase comprises 55–64% of the phenocryst assem-

blage and has a crystal size of 0.6–1.2 mm. The plagioclase SiO2 content varies from 57.81 to 64.23 wt.% (average = 60.13 wt.%), and An values mostly cluster in the range 31.4–37.2 (andesine), although a small amount of the plagioclase is oligoclase (An = 18.0–23.4). In the granodiorite porphyry, plagioclase represents 70–75% of the total phenocryst content, and most plagioclase crystals have well-developed oscillatory zoning with a crystal size

of 0.3–2.0 mm. These plagioclases have SiO2 contents of 57.56– 62.02 wt.% (average = 60.35 wt.%), and An values from 31.6 to 42.9 (andesine). Therefore, plagioclase in the Tongshan intrusion is mainly andesine with subordinate amounts of oligoclase (Fig. 4a).

4.1.2. Biotite Biotite occurs as euhedral, sheet-like phenocrysts (Fig. 3). In the Fig. 3. Microstructures in representative rocks from the Tongshan intrusion viewed in transmitted and cross-polarized light. (a) Quartz diorite porphyry; (b) Quartz quartz monzonite porphyry, biotite comprises 24% of the total phe- monzonite porphyry; and (c) Granodiorite porphyry. Bit = biotite; Hb = hornblende; nocryst content, whereas smaller amounts of chloritized biotite are Pl = plagioclase; Qz = quartz. present in the quartz diorite porphyry and granodiorite porphyry. The major element chemistry of the biotite is listed in Table 2. Bio-

tite SiO2 contents vary from 35.39 to 37.76 wt.% (aver- grain size of 200 mesh. An ion microprobe was used for zircon U– age = 36.83 wt.%). The MgO contents range from 11.55 to Pb dating of the quartz monzonite porphyry, with a SHRIMP II 15.15 wt.% (average = 13.28 wt.%), and are typical of values at the instrument in the Beijing Ion Probe Center, Beijing, China. Details crust-mantle transition. Biotite FeO/MgO ratios range from 1.04 of the ion microprobe analysis procedures are described in Wil- to 1.86 (average = 1.38) and are similar to those for biotite from liams (1998). Representative zircons with euhedral crystal shapes calc-alkaline granitoids (1.76). The Mg/(Mg + Fe) values for the bio- were selected by handpicking under a binocular microscope, were tite vary from 0.52 to 0.67 (average = 0.60), which is higher than mounted in epoxy resin along with a working standard zircon values for biotite from S-type granitoids (0.4; Liu and Wang, (TEM; age = 416.8 Ma), and were then polished and gold coated. 1994). Biotite tetrahedral AlVI values (<0.024) are also lower than Microphotographs of the zircons were taken in transmitted and corresponding values for biotite from S-type granites (0.353– 796

Table 1 Chemical compositions (%) of representative plagioclases in Tongshan intrusion.

Lithology Quartz diorite porphyry Quartz monzonite porphyry Granodiorite porphyry .Y hn ta./Junlo sa at cecs7 21)792–809 (2014) 79 Sciences Earth Asian of Journal / al. et Zhang Z.-Y.

Sample QS1-1b 1 QS1-2b 1 QS1-3b 1 QS1-4b 1 QS1-4b 2 QS2-1b 1 QS2-2b 1 QS2-3b 1 QS2-3b 2 QS2-3b 3 QS3-1b 1 QS3-1b 2 QS3-1b 3 QS3-1b 4 QS3-1b 5

SiO2 61.60 62.22 60.10 60.78 62.28 57.81 59.99 58.99 59.61 64.23 62.02 60.51 57.56 60.64 61.01 TiO2 0.00 0.01 0.00 0.01 0.00 0.00 0.29 0.03 0.01 0.00 0.02 0.02 0.00 0.00 0.00 Al2O3 24.42 23.95 25.21 24.36 23.75 25.53 24.01 25.35 24.44 22.80 24.29 24.37 26.48 25.18 24.18 FeO 0.16 0.14 0.22 0.15 0.19 0.23 0.58 0.25 0.22 0.21 0.27 0.21 0.24 0.23 0.27 MnO 0.03 0.00 0.02 0.01 0.03 0.00 0.00 0.02 0.00 0.00 0.00 0.04 0.00 0.01 0.02 MgO 0.00 0.00 0.02 0.01 0.00 0.02 0.06 0.01 0.00 0.11 0.02 0.00 0.03 0.03 0.02 CaO 6.38 5.84 7.41 6.26 5.61 7.97 5.32 7.21 6.60 3.48 6.54 6.56 8.62 6.70 6.28 Na2O 7.41 7.69 6.74 7.41 7.69 7.15 9.35 7.08 7.60 8.58 7.08 6.93 6.19 7.08 7.22 K2O 0.38 0.47 0.39 0.46 0.43 0.44 0.39 0.44 0.57 0.24 0.66 0.52 0.23 0.36 0.45 Total 100.38 100.32 100.11 99.45 99.98 99.15 99.99 99.38 99.05 99.65 100.90 99.16 99.35 100.23 99.45 Si 2.726 2.751 2.675 2.717 2.761 2.617 2.689 2.652 2.688 2.834 2.733 2.713 2.593 2.690 2.726 Al 1.273 1.247 1.322 1.282 1.240 1.361 1.268 1.342 1.298 1.185 1.260 1.287 1.405 1.316 1.272 3+ Fe 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Ti 0.000 0.000 0.000 0.000 0.000 0.000 0.010 0.001 0.000 0.000 0.001 0.001 0.000 0.000 0.000 Fe2+ 0.006 0.005 0.008 0.006 0.007 0.009 0.022 0.010 0.008 0.008 0.010 0.008 0.009 0.009 0.010 Mn 0.001 0.000 0.001 0.001 0.001 0.000 0.000 0.001 0.000 0.000 0.000 0.002 0.000 0.001 0.001 Mg 0.000 0.000 0.001 0.001 0.000 0.001 0.004 0.001 0.000 0.007 0.001 0.000 0.002 0.002 0.001 Ca 0.303 0.277 0.354 0.300 0.267 0.387 0.256 0.347 0.319 0.165 0.309 0.315 0.416 0.319 0.301 Na 0.636 0.659 0.582 0.642 0.661 0.628 0.813 0.617 0.665 0.734 0.605 0.603 0.541 0.609 0.626 K 0.022 0.027 0.022 0.026 0.024 0.026 0.022 0.025 0.033 0.014 0.037 0.030 0.013 0.021 0.026 Sum 4.965 4.966 4.964 4.974 4.960 5.027 5.083 4.996 5.010 4.946 4.956 4.957 4.979 4.965 4.962 Ab 66.2 68.5 60.8 66.3 69.5 60.4 74.5 62.4 65.4 80.5 63.6 63.6 55.7 64.2 65.7 An 31.5 28.8 36.9 31.0 28.0 37.2 23.4 35.1 31.4 18.0 32.5 33.3 42.9 33.6 31.6 Or 2.2 2.8 2.3 2.7 2.5 2.5 2.0 2.6 3.2 1.5 3.9 3.1 1.4 2.2 2.7 Z.-Y. Zhang et al. / Journal of Asian Earth Sciences 79 (2014) 792–809 797

formula (0.055–0.220) and has a high Mg# [Mg/(Mg + Fe) = 0.60– 0.75]. The chemistry of the hornblende is consistent with the composition of amphibole generally found in I-type granitoids (Cle- ments and Wall, 1984).

4.2. SHRIMP zircon U–Pb dating

In the quartz monzonite porphyry of the Tongshan intrusion, euhedral zircons are colorless and transparent. The zircons are 100–200-lm-long and have length–width ratios of 1.5:1 to 4:1 (Fig. 6). Zircon CL imaging is an effective way to distinguish magmatic from metamorphic zircon (Vavra et al., 1996). The CL characteristics of zircon reflect the content of trace elements in zircon and, particularly, rare earth element (REE), U, and Th concentrations (Hanchar and Miller, 1993). Most of the zircons have distinct cores (dark CL) and rims (bright CL), and exhibit oscillatory zoning in the core, which reflect differences in U and Th contents. The variable U (59–1261 lg/g) and Th (41–524 lg/g) contents of these zircons are highlighted in Table 4, which also have a large range of Th/ U ratios (0.43–1.48). Thorium and U contents generally exhibit a positive correlation (Fig. 7a). These zoning features and Th/U ratios demonstrate that the zircon has a magmatic origin. It is also note- worthy that individual zircons with core–rim structures, high CL intensity, and Th/U > 0.4, but insignificant zoning, also appear to have a magmatic origin. However, we interpret such zircons as being ancient magmatic zircons of xenocrystic origin. Due to the old age of these xenocrystic zircons and influence of subsequent metamorphism, their original oscillatory zoning has been over- printed. The 206Pb/238U apparent ages of 24 analyses of zircon range from 139.0 to 152.0 Ma (Table 4), and are concordant (n = 24) (Fig. 7b). However, the other three apparent ages are 2315.4 Ma, 842.9 Ma, and 406.8 Ma, perhaps reflecting contamination of the Mesozoic magmatism by ancient basement rocks. The weighted average 206Pb/238U zircon age is 145.1 ± 1.2 Ma (n = 24; MSWD = 1.3) (Fig. 7c), which we take to represent the crystallization age of the quartz monzonite porphyry.

4.3. Whole-rock geochemistry

Major and trace element data for representative samples of the Tongshan intrusion are listed in Table 5. The quartz diorite por-

phyry has a limited variation in SiO2 content (60.23–62.72 wt.%; Fig. 4. (a) Ternary plots of plagioclase compositions (after Pan et al., 1994). (b) average = 61.05 wt.%). The K O/Na O values range from 1.00 to Biotite classification diagram (after Foster, 1960). 2 2 2.88 (average = 1.67), and total alkali concentrations are high (Na2- O+K2O = 4.97–6.30 wt.%; average = 5.77 wt.%). The Al2O3 contents 0.561; Whalen and Chappell, 1988). Biotite in the Tongshan intru- vary from 15.31 to 17.50 wt.% (average = 16.73 wt.%). The MgO and sion can be classified as magnesio-biotite (Fig. 4b), and is marked CaO contents are both low, with averages of 2.36 wt.% and VI by being Mg-rich and low in Al , which is diagnostic of biotite 4.93 wt.%, respectively. In the quartz monzonite porphyry, SiO2 from I-type granitoids. contents vary from 61.82 to 63.18 wt.% (average = 62.73 wt.%). The K2O/Na2O values vary from 0.53 to 0.85 (average = 0.71) and total alkali contents are high (Na2O+K2O = 7.99–8.72 wt.%; aver- 4.1.3. Hornblende age = 8.31 wt.%). The Al2O3 contents range from 14.30 to Hornblende occurs as euhedral to subhedral phenocrysts 16.10 wt.% (average = 15.24 wt.%), whereas MgO contents are very (Fig. 3). The chemical compositions of representative analyzed low, with an average of 1.86 wt.%, and CaO contents have an aver- hornblende are listed in Table 3. In the quartz diorite porphyry, age of 3.15 wt.%. In the granodiorite porphyry, the SiO2 content is hornblende comprises 15–19% of the phenocryst assemblage and high (66.23 wt.%). The K2O/Na2O value is 1.34 and the total alkali exhibits a wide range in crystal size (0.5–2.5 mm). Length–width content is also high (Na2O+K2O = 7.42 wt.%). The Al2O3, MgO, ratios of the hornblende range from 2:1 to 5:1. Chloritization has and CaO contents are 14.75, 1.63, and 3.08 wt.%, respectively. In affected the hornblende to varying extents. In the quartz monzo- general, all of the samples are silica- and alkali-rich, whereas they nite porphyry, hornblende forms <9% of the total phenocryst con- are Ca- and Mg-poor. The quartz diorite porphyry has the lowest tent and has a crystal size of 0.5–0.6 mm. In the granodiorite content of total alkalis, whereas the quartz monzonite porphyry porphyry, hornblende comprises 13–20% of the total phenocryst has the highest alkalinity. In a plot of K2O versus SiO2 (Fig. 8a), content and has a crystal size of 0.1–0.5 mm. According to the all the samples fall in the field for the high-K, calc-alkaline rocks. amphibole classification scheme of Leake et al. (1997), hornblende Most of the samples are aluminous (Fig. 8b), with the quartz diorite in the Tongshan intrusion is mainly magnesio-hornblende and porphyry having the highest alumina saturation index (A/CNK; edenite (Fig. 5). Almost all the hornblende is Ti-poor in chemical average = 1.02), although some other individual samples are 798

Table 2 Chemical compositions (%) of representative biotites in Tongshan intrusion.

Lithology Quartz diorite porphyry Quartz monzonite porphyry Granodiorite porphyry

Sample QS 1-1b1 QS1-2b1 QS1-3b1 QS1-4b1 QS1-4b2 QS2-1b1 QS2-2b1 QS2-3b1 QS2-3b2 QS2-3b3 QS3-1b1 QS3-1b2 QS3-1b 3 QS3-1b4 QS3-1b5 .Y hn ta./Junlo sa at cecs7 21)792–809 (2014) 79 Sciences Earth Asian of Journal / al. et Zhang Z.-Y. SiO2 36.42 37.31 37.00 37.50 37.74 36.30 35.75 37.75 36.95 36.46 37.76 36.47 37.53 36.13 35.39 TiO2 5.04 4.87 4.72 4.86 4.88 4.63 4.66 4.05 3.19 4.58 4.50 4.57 4.30 4.91 4.25 Al2O3 13.16 12.32 13.38 13.10 13.32 13.53 13.59 13.49 13.27 13.27 12.94 13.60 13.28 13.46 14.09 FeO 19.63 21.43 19.36 18.02 17.56 15.80 17.42 15.70 15.52 16.67 17.51 19.29 17.60 19.51 20.58 MnO 0.23 0.30 0.26 0.29 0.23 0.41 0.13 0.00 0.05 0.15 0.22 0.22 0.17 0.29 0.27 MgO 12.35 11.55 12.66 12.78 12.65 13.17 13.13 15.15 14.75 13.82 14.11 13.39 13.37 13.16 13.21 CaO 0.03 0.14 0.00 0.06 0.03 0.00 0.12 0.01 0.13 0.00 0.00 0.00 0.00 0.07 0.09 Na2O 0.21 0.13 0.16 0.21 0.15 0.22 0.40 0.11 0.15 0.27 0.21 0.17 0.23 0.19 0.14 K2O 9.34 10.31 9.12 8.71 9.06 9.29 9.07 9.32 9.11 9.37 9.49 9.02 9.19 9.07 7.65 Total 96.41 98.36 96.66 95.53 95.62 93.35 94.27 95.58 93.12 94.59 96.74 96.73 95.67 96.79 95.67 Si 5.489 5.586 5.532 5.617 5.638 5.552 5.460 5.603 5.638 5.526 5.601 5.455 5.617 5.419 5.352 AlIV 2.337 2.174 2.357 2.312 2.345 2.439 2.446 2.360 2.362 2.370 2.262 2.397 2.343 2.379 2.511 AlVI 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.024 0.000 0.000 0.000 0.000 0.000 0.000 Fe3+ 0.325 0.288 0.343 0.365 0.363 0.314 0.295 0.298 0.283 0.293 0.306 0.312 0.330 0.306 0.350 Fe2+ 2.149 2.395 2.077 1.892 1.831 1.707 1.929 1.650 1.697 1.820 1.866 2.101 1.873 2.141 2.252 Ti 0.571 0.548 0.531 0.548 0.548 0.533 0.535 0.452 0.366 0.522 0.502 0.514 0.484 0.554 0.483 Mn 0.029 0.038 0.033 0.037 0.029 0.053 0.017 0.000 0.006 0.019 0.028 0.028 0.022 0.037 0.035 Mg 2.775 2.578 2.822 2.854 2.817 3.003 2.989 3.352 3.355 3.123 3.120 2.986 2.983 2.943 2.978 Ca 0.005 0.022 0.000 0.010 0.005 0.000 0.020 0.002 0.021 0.000 0.000 0.000 0.000 0.011 0.015 Na 0.061 0.038 0.046 0.061 0.043 0.065 0.118 0.032 0.044 0.079 0.060 0.049 0.067 0.055 0.041 K 1.796 1.969 1.739 1.664 1.726 1.812 1.767 1.765 1.773 1.812 1.796 1.721 1.755 1.735 1.476 Sum 15.537 15.638 15.480 15.359 15.345 15.478 15.577 15.514 15.570 15.565 15.541 15.562 15.473 15.580 15.493 2+ 2+ Fe /(Fe + Mg) 0.44 0.48 0.42 0.40 0.39 0.36 0.39 0.33 0.34 0.37 0.37 0.41 0.39 0.42 0.43 Mg/(Fe2+ + Mg) 0.56 0.52 0.58 0.60 0.61 0.64 0.61 0.67 0.66 0.63 0.63 0.59 0.61 0.58 0.57 TAl 2.34 2.17 2.36 2.31 2.34 2.44 2.45 2.36 2.39 2.37 2.26 2.40 2.34 2.38 2.51 P/kbar 0.55 0.06 0.61 0.48 0.58 0.86 0.88 0.62 0.70 0.65 0.32 0.73 0.57 0.68 1.08 H/km 1.82 0.19 2.02 1.57 1.90 2.84 2.91 2.05 2.31 2.15 1.07 2.42 1.87 2.24 3.56 Table 3 Chemical compositions (%) of representative hornblendes in Tongshan intrusion.

Lithology Quartz diorite porphyry Quartz monzonite porphyry Granodiorite porphyry

Sample QS 1-1b1 QS1-2b1 QS1-3b1 QS1-4b1 QS1-4b2 QS2-1b1 QS2-2b1 QS2-3b1 QS2-3b2 QS2-3b3 QS3-1b1 QS3-1b2 QS3-1b3 QS3-1b4 QS3-1b5

SiO2 49.51 47.43 49.68 49.62 45.06 46.14 46.91 44.97 47.08 44.81 50.24 45.45 45.05 46.72 50.41 TiO2 1.15 1.61 1.04 0.97 1.59 1.35 1.10 1.96 1.42 1.07 0.50 1.53 1.48 1.44 0.64 .Y hn ta./Junlo sa at cecs7 21)792–809 (2014) 79 Sciences Earth Asian of Journal / al. et Zhang Z.-Y. Al2O3 5.43 6.80 5.24 4.60 6.80 7.55 6.26 8.85 7.26 8.29 3.45 8.52 8.45 7.59 4.30 FeO 13.63 16.13 14.85 14.60 16.63 14.80 13.50 15.09 14.49 17.46 13.08 15.94 15.65 14.40 12.49 MnO 0.44 0.50 0.49 0.44 0.45 0.40 0.59 0.57 0.44 0.40 0.34 0.41 0.47 0.39 0.32 MgO 14.28 12.23 13.42 13.89 12.41 12.95 14.10 12.26 13.26 11.54 15.74 11.67 12.31 13.07 15.49 CaO 10.91 10.93 10.78 11.65 11.57 12.03 11.92 10.60 11.08 11.47 12.20 10.92 10.73 10.94 11.37 Na2O 1.28 1.57 1.18 1.05 1.39 1.46 2.87 1.75 1.49 1.21 0.82 1.64 1.70 1.55 1.05 K2O 0.55 0.70 0.42 0.56 0.89 0.90 0.71 1.01 0.78 1.24 0.33 1.00 0.89 0.68 0.36 Total 97.18 97.90 97.10 97.38 96.79 97.58 97.96 97.06 97.30 97.49 96.70 97.08 96.73 96.78 96.43 T Si 7.240 7.011 7.297 7.287 6.763 6.833 6.962 6.699 6.942 6.695 7.332 6.797 6.727 6.920 7.359 Al 0.760 0.989 0.703 0.713 1.200 1.167 1.038 1.301 1.058 1.305 0.593 1.203 1.273 1.080 0.641 3+ Fe 0.000 0.000 0.000 0.000 0.038 0.000 0.000 0.000 0.000 0.000 0.075 0.000 0.000 0.000 0.000 C Al 0.175 0.195 0.204 0.082 0.002 0.150 0.056 0.251 0.203 0.154 0.000 0.298 0.213 0.244 0.098 Fe3+ 0.325 0.290 0.337 0.232 0.450 0.224 0.030 0.372 0.320 0.499 0.363 0.285 0.414 0.326 0.318 Ti 0.126 0.179 0.115 0.107 0.179 0.150 0.123 0.220 0.157 0.120 0.055 0.172 0.166 0.160 0.070 Mg 3.113 2.695 2.939 3.041 2.777 2.859 3.120 2.722 2.915 2.570 3.425 2.602 2.740 2.886 3.371 Fe2+ 1.233 1.610 1.376 1.511 1.563 1.591 1.635 1.399 1.377 1.632 1.136 1.617 1.437 1.359 1.123 Mn 0.027 0.031 0.030 0.027 0.028 0.025 0.037 0.036 0.027 0.025 0.021 0.026 0.029 0.024 0.020 BFe2+ 0.109 0.095 0.112 0.050 0.036 0.017 0.011 0.108 0.089 0.051 0.022 0.091 0.103 0.099 0.084 Mn 0.028 0.032 0.031 0.028 0.029 0.025 0.037 0.036 0.028 0.025 0.021 0.026 0.030 0.025 0.020 Ca 1.709 1.731 1.697 1.833 1.860 1.909 1.895 1.692 1.750 1.836 1.908 1.750 1.717 1.736 1.778 Na 0.154 0.143 0.161 0.089 0.074 0.049 0.056 0.163 0.133 0.087 0.049 0.133 0.150 0.140 0.118 A Na 0.209 0.307 0.175 0.210 0.330 0.371 0.770 0.342 0.293 0.263 0.183 0.343 0.342 0.305 0.179 K 0.103 0.132 0.079 0.105 0.170 0.170 0.134 0.192 0.147 0.236 0.061 0.191 0.170 0.128 0.067 Sum 15.311 15.439 15.254 15.315 15.501 15.541 15.905 15.534 15.440 15.500 15.244 15.533 15.511 15.434 15.246 # Mg 0.70 0.61 0.66 0.66 0.63 0.64 0.65 0.64 0.67 0.60 0.75 0.60 0.64 0.66 0.74 P/kbar 0.50 1.55 0.38 0.10 1.62 2.11 1.17 3.10 1.87 2.71 0.95 2.89 2.83 2.14 0.33 H/km 1.63 5.11 1.24 0.32 5.36 6.97 3.85 10.25 6.18 8.95 3.14 9.53 9.33 7.06 1.10 t/°C 671 705 671 667 755 759 707 768 723 727 672 746 788 728 652

# 2+ Mg = Mg/(Mg + Fe ). 799 800 Z.-Y. Zhang et al. / Journal of Asian Earth Sciences 79 (2014) 792–809

Fig. 5. Hornblende classiﬁcation diagram (after Leake et al., 1997).

Fig. 6. Cathodoluminescence images of zircon crystals from quartz monzonite porphyry of the Tongshan intrusion. peraluminous. Within the sample suite, SiO2 contents increase in close relationship in their magma source. In the quartz diorite por- the sequence: quartz diorite porphyry ? quartz monzonite porphyry, RREE, light REE/heavy REE, (La/Yb)N, (La/Sm)N, (Gd/Yb)N, phyry ? granodiorite porphyry. However, Al2O3, CaO, MgO, TiO2, and dEu average 157.37 lg/g, 12.59 17.39, 5.47, 2.54, and 1.10, and total alkalis do not exhibit good linear correlations with SiO2, respectively. For the quartz monzonite porphyry, these values are suggesting that the three lithologies are not simply related by frac- 127.76 lg/g, 12.32, 16.72, 5.16, 2.59, and 1.22, and for the granodi- tional crystallization. orite porphyry, these values are 141.05 lg/g, 12.86, 17.36, 5.27, Chondrite-normalized REE patterns are shown in Fig. 9a. All of 2.67, and 1.23. These results show that total REE contents of all the samples have similar light REE enriched patterns, indicating a the rocks are low (<200 lg/g) and decrease in the sequence: quartz Z.-Y. Zhang et al. / Journal of Asian Earth Sciences 79 (2014) 792–809 801

Table 4 SHRIMP zircon U–Pb results for representative quartz monzonite porphyry.

206 232 238 206 ⁄ 238 206 207 206 206 238 Plot Pbc (%) U (lg/g) Th (lg/g) Th/ U Pb (lg/g) Total n ( U)/n ( Pb) Error (%) Total n ( Pb)/n ( Pb) Error (%) Pb/ U Age (Ma) 1.1 3.57 113 70 0.64 2.20 44.23 2.2 0.0739 3.8 139.0 ± 3.5 2.1 2.73 73 46 0.65 1.43 43.7 2.7 0.0699 4.7 142.0 ± 3.8 3.1 0.00 120 88 0.75 2.47 41.92 2.2 0.0616 6.8 152.0 ± 3.4 4.1 – 99 63 0.66 1.87 45.4 2.4 0.0642 4.2 142.2 ± 3.5 5.1 0.71 201 125 0.64 4.12 42.03 1.9 0.0613 2.9 150.5 ± 2.9 6.1 0.46 172 132 0.79 3.34 44.30 2.1 0.0551 3.4 143.2 ± 3.1 7.1 0.08 1261 524 0.43 25.3 42.73 1.6 0.04883 1.3 149.0 ± 2.4 8.1 2.52 104 66 0.66 2.04 43.9 3.1 0.0712 4.1 141.7 ± 4.6 9.1 0.69 252 208 0.85 4.92 43.94 1.9 0.0583 5.5 144.1 ± 2.7 10.1 – 319 150 0.49 6.25 43.80 1.9 0.0551 2.5 145.9 ± 2.7 11.1 0.71 207 129 0.64 4.08 43.52 1.9 0.0609 3.9 145.4 ± 2.9 12.1 0.08 119 77 0.67 2.29 44.84 2.2 0.0697 3.7 142.1 ± 3.1 13.1 0.23 516 366 0.73 9.90 44.79 1.7 0.05245 1.9 142.0 ± 2.4 14.1 2.31 78 59 0.78 1.59 42.3 2.5 0.0640 6.5 147.2 ± 3.8 15.1 1.66 195 122 0.65 3.86 43.3 2.4 0.0726 4.6 144.6 ± 3.4 16.1 0.00 360 496 1.42 7.12 43.43 2.0 0.0530 2.4 146.7 ± 2.9 17.1 0.64 122 103 0.88 2.46 42.45 2.2 0.0606 4.0 149.2 ± 3.2 18.1 0.24 124 82 0.69 14.9 7.14 2.1 0.0965 1.7 842.9 ± 16.6 19.1 0.38 66 41 0.64 3.68 15.29 2.3 0.1472 2.3 406.8 ± 9.1 20.1 1.38 131 98 0.77 2.70 41.50 2.3 0.0639 4.2 151.4 ± 3.7 21.1 – 98 75 0.79 1.92 44.06 2.2 0.0682 5.5 145.1 ± 3.2 22.1 0.67 142 136 0.99 2.79 43.72 2.1 0.0607 4.0 144.8 ± 3.0 23.1 0.91 341 143 0.43 6.67 43.97 1.8 0.0552 3.1 143.7 ± 2.6 24.1 0.13 229 133 0.60 4.44 44.30 1.9 0.0569 3.9 143.7 ± 2.7 25.1 – 161 132 0.85 3.02 45.87 2.1 0.0643 3.5 139.1 ± 2.8 26.1 0.56 360 198 0.57 7.22 42.88 2.0 0.0615 2.7 147.8 ± 2.9 27.1 0.06 59 85 1.48 22 2.313 1.9 0.1630 0.82 2315.4 ± 37.2

Fig. 7. (a) Th–U contents of zircons. (b) Concordia plots of zircon U–Pb age data. (c) Weighted average 206Pb/238U age based on 24 analyses of zircon from quartz monzonite porphyry of the Tongshan intrusion. diorite porphyry ? quartz monzonite porphyry ? granodiorite of rocks are enriched in the most incompatible elements, large ion porphyry. Rare earth element fractionation is signiﬁcant (e.g., lithophile element-rich (e.g., K, Rb, and Ba), but exhibit signiﬁcant

[La/Yb]N > 15), and reflects the light REE enrichment of the sam- negative anomalies in some high field strength elements (e.g., Nb, ples. Europium generally exhibits a positive anomaly, which is Ta, P, and Ti). due to the rocks being plagioclase-rich, but not having experienced significant fractional crystallization during their formation. In 5. Discussion addition, the hornblende content of these rocks is relatively small and may suggest that hornblende accumulation occurred during 5.1. Age implications magma emplacement, which could have resulted in separation of hornblende from the melt and formation of a positive Eu anomaly. Mesozoic magmatism in the MLYRB is an important feature of In primitive-mantle-normalized diagrams (Fig. 9b), the three types the large-scale evolution and metallogenesis during thinning of 802 Z.-Y. Zhang et al. / Journal of Asian Earth Sciences 79 (2014) 792–809

Table 5 Major (%), trace (lg/g) and rare earth elemental (lg/g) results for representative rocks.

Samples Quartz diorite porphyry Quartz monzonite porphyry Granodiorite porphyry QS1-1 QS1-2 QS1-3 QS1-4 QS2-1 QS2-2 QS2-3 QS3-1

SiO2 60.44 60.80 62.72 60.23 63.17 61.82 63.18 66.23

Al2O3 17.50 17.18 15.31 16.94 15.32 16.10 14.30 14.75

TFe2O3 3.28 3.71 3.90 5.21 5.84 6.62 5.70 3.76 CaO 4.74 5.66 4.57 4.76 3.69 3.16 2.61 3.08 MgO 2.68 2.63 1.21 2.92 1.72 1.97 1.90 1.63

K2O 3.69 3.08 3.88 3.07 3.76 3.44 3.01 4.24

Na2O 1.28 3.09 2.42 2.57 4.44 4.55 5.71 3.18 MnO 0.107 0.099 0.050 0.071 0.053 0.038 0.025 0.048

TiO2 0.570 0.634 0.536 0.643 0.460 0.454 0.468 0.422

P2O5 0.667 0.280 0.666 0.299 0.197 0.174 0.171 0.159 LOI 4.85 2.70 4.43 3.14 1.07 1.01 1.65 2.18 Total 99.81 99.86 99.69 99.84 99.73 99.34 98.73 99.68 A/CNK 1.19 0.92 0.93 1.05 0.85 0.95 0.82 0.96 A/NK 2.87 2.04 1.87 2.24 1.35 1.44 1.13 1.50

K2O/Na2O 2.88 1.00 1.60 1.19 0.85 0.76 0.53 1.34

Li 7.29 5.16 6.15 11.10 7.94 9.49 9.26 7.77 Be 0.78 1.11 1.04 1.01 1.04 0.98 0.94 1.00 Sc 5.34 8.19 5.07 7.94 5.44 5.37 5.28 4.56 V 59.40 81.71 62.77 87.91 63.03 62.87 61.27 50.84 Co 14.01 23.15 9.70 7.58 7.00 14.74 14.89 5.04 Cu 225.10 56.68 14.49 39.32 618 4155 4376 16.32 Ga 17.78 16.58 18.09 19.02 18.98 19.83 18.77 17.67 Rb 85.10 74.89 85.90 82.14 97.95 69.35 70.78 89.75 Sr 516.80 528 606 578 566 611 619 610 Y 11.78 15.89 11.91 11.46 11.41 10.38 10.65 11.48 Zr 190.2 149.00 118.40 188.4 190.0 136.60 165.80 178.8 Nb 12.66 13.88 12.96 12.26 12.64 17.78 12.14 12.82 Sn 1.64 2.78 1.89 1.50 1.60 1.57 1.97 1.51 Cs 8.31 2.75 2.66 3.97 3.73 2.00 1.99 1.03 Ba 850 875 949 853 972 899 897 969 Hf 5.00 3.99 3.32 4.73 5.09 3.68 4.29 4.89 Ta 1.02 0.92 1.09 1.01 1.10 1.03 0.97 0.98 Tl 9.42 0.33 0.36 0.30 0.48 0.35 0.32 0.33 Pb 21.97 13.01 8.92 17.78 9.13 15.10 13.34 12.40 Th 11.36 12.85 11.38 11.70 14.23 10.42 10.46 14.17 U 2.93 2.43 3.32 2.69 3.45 2.33 2.50 2.96

La 36.71 40.01 38.73 35.22 32.97 27.44 27.95 32.08 Ce 68.82 68.43 70.92 65.62 62.20 52.60 54.18 63.44 Pr 6.99 7.85 7.12 6.62 6.55 5.32 5.56 6.41 Nd 26.02 29.35 26.11 24.28 23.84 19.92 20.83 23.50 Sm 4.31 5.01 4.26 3.85 3.90 3.37 3.48 3.83 Eu 1.52 1.61 1.65 1.66 1.54 1.43 1.45 1.61 Gd 4.51 5.33 4.53 4.13 4.10 3.57 3.72 4.13 Tb 0.52 0.66 0.51 0.48 0.48 0.42 0.43 0.47 Dy 2.46 3.35 2.47 2.35 2.39 2.06 2.13 2.30 Ho 0.46 0.64 0.46 0.45 0.45 0.39 0.40 0.43 Er 1.30 1.86 1.33 1.33 1.32 1.12 1.15 1.23 Tm 0.19 0.27 0.19 0.20 0.19 0.16 0.17 0.18 Yb 1.30 1.89 1.36 1.40 1.31 1.11 1.13 1.25 Lu 0.20 0.28 0.20 0.21 0.20 0.17 0.17 0.19 RREE 155.31 166.53 159.84 147.78 141.45 119.08 122.76 141.05 LREE 144.38 152.26 148.78 137.25 131.00 110.07 113.46 130.87 HREE 10.94 14.27 11.06 10.54 10.45 9.01 9.30 10.17 LREE/HREE 13.20 10.67 13.45 13.02 12.54 12.22 12.20 12.86

(La/Yb)N 19.08 14.31 19.20 16.97 16.92 16.62 16.62 17.36

(La/Sm)N 5.36 5.03 5.73 5.75 5.31 5.13 5.05 5.27

(Gd/Yb)N 2.81 2.28 2.69 2.38 2.52 2.59 2.65 2.67 dEu 1.05 0.95 1.14 1.26 1.17 1.25 1.23 1.23 dCe 0.97 0.88 0.96 0.97 0.96 0.99 0.99 1.01

continental lithosphere in eastern China. Formation ages of mag- isochron age (142 Ma) (Zhou, 1997), suggesting Early Cretaceous matic rocks are concentrated between 156 and 124 Ma in this re- emplacement. However, these chronometers have relatively low gion (Zhou et al., 2008a; Mao et al., 2011; Wu et al., 2012; Xie closure temperatures and are susceptible to metamorphism and et al., 2012b), and the magmatism displays an evolutionary trend alteration meaning that they most likely reﬂect minimum ages. with time (Zhou et al., 2008b). The Tongshan intrusion is represen- The zircon U–Pb isotopic dating system is less susceptible to later tative of intrusive rocks in the Guichi district of the Yangtze River geological disturbances and has a high closure temperature, mean- valley. Previous geochronological data for the intrusion included a ing that the obtained age will most reliably represent the mag- K–Ar biotite (139 Ma) and Rb–Sr whole rock–single mineral matic crystallization age. As such, our SHRIMP zircon U–Pb age Z.-Y. Zhang et al. / Journal of Asian Earth Sciences 79 (2014) 792–809 803

Fig. 8. (a) K2O versus SiO2 plots for representative rocks from the Tongshan intrusion (ﬁelds in the plot are from Rickwood, 1989). (b) Plot of A/NK versus A/CNK

{A/NK = molar ratio of [Al2O3/(Na2O+K2O)]; A/CNK = molar ratio of [Al2O3/

(CaO + Na2O+K2O)]}. Fig. 9. (a) Chondrite-normalized REE patterns (Boynton, 1984). (b) Primitive- mantle-normalized spiderdiagrams (Sun and McDonough, 1989). of 145.1 ± 1.2 Ma represents the formation age of the quartz monzonite porphyry in middle Yanshanian times during the Late Juras- In the Tongshan intrusion, the main quartz diorite porphyry, sic. This is slightly older than the Yueshan intrusion quartz monzonite porphyry, and granodiorite porphyry lithologies (138.7 ± 0.5 Ma to 139.3 ± 1.5 Ma) in the Anqing section of the are closely associated and reﬂect a continuum of lithologies rather Anqing–Guichi district (Zhang et al., 2008; Liu et al., 2009). Most than discrete units. All of these lithologies have similar REE and magmatic rocks in the MLYRB have ages of 145–120 Ma (Chen trace element chemistry, which suggests that the various rock et al., 2005; Du et al., 2007), suggesting that the Tongshan intrusion units in the intrusion have similar sources. However, no clear lin- was emplaced early in this period of magmatism and is consistent ear relationship is observed between major elements, Rb/Sr, Rb, with the suggested an inland (Jiujiang) to coastal younging of ages and SiO2 in the various lithologies, and Eu consistently exhibits a along a northeasterly trend (Zhou et al., 2008a). small positive anomaly. All of the samples fall in the OGT (granitoids formed without differentiation) ﬁeld in a plot of (K2O+Na2- O)/CaO versus Zr + Nb + Ce + Y (Fig. 10a). The above observations 5.2. Source characteristics and petrogenetic model all indicate that the three lithologies cannot be simply explained by a fractional crystallization sequence. In a plot of La/Sm versus Magmatism in the MLYRB occurred episodically in time and La (Fig. 10b), data for all but one sample fall broadly along a sloping space (Zhou et al., 2008b), and the resulting rocks have different straight line, which indicates that the magmas of the Tongshan origins. Some studies have concluded that Mesozoic intermediate intrusion were primarily produced by batch-type partial melting. to acid magmatic rocks in the MLYRB are mainly the result of Trace element and Sr isotope data can be used to more robustly crust–mantle interaction (Tao et al., 1998; Chen and Jiang, 1999; identify the magma sources of the rocks. The REE patterns of rocks Du et al., 2004, 2007; Xu et al., 2004), and formed by fractional in the Tongshan intrusion exhibit light REE enrichment ([La/ crystallization after basaltic magma generated by enriched litho- Yb]N > 10), are low in total REE (<200 lg/g), and have small posi- spheric mantle melting had assimilated crustal rocks. However, tive Eu anomalies (average dEu = 1.16). These REE characteristics other studies have proposed that these rocks are the products of are inconsistent with those of crustally derived granitoids, suggest- the partial melting of lower crust (Xu et al., 2001; Robert et al., ing that these magmas originated in the mantle. In a plot of (La/

2002; Zhu et al., 2003). Lou and Du (2006) considered that late Yb)N versus dEu (Fig. 10c), data for all samples fall in the crust– Mesozoic A-type granites formed from dioritic magmas generated mantle type ﬁeld. Moreover, some Archean–early Paleozoic ages by partial melting of metasomatized mantle that subsequently in the zircon population from these rocks require assimilation experienced fractional crystallization of hornblende, plagioclase, and contamination of the Mesozoic mantle-derived magmas by an- and titanomagnetite. cient crustal rocks. Strontium isotopic studies (Chen et al., 1993; 804 Z.-Y. Zhang et al. / Journal of Asian Earth Sciences 79 (2014) 792–809

Fig. 11. (a) Plot of TiO2 versus Al2O3 for hornblende (after Jiang and An, 1984). (b) Plot of RFeO/(RFeO + MgO) versus MgO for biotite (after Zhou, 1986).

shallow crystallization after ascent and emplacement of magma that had experienced variable degrees of crustal contamination deep in the crust. This magma formed by mixing between basaltic magma generated by variable degrees of partial melting of enriched lithospheric mantle and lower crust, and experienced no signiﬁcant fractional crystallization.

5.3. Physico-chemical crystallization conditions and significance for Fig. 10. Plots of (a) (K O+Na O)/CaO versus Zr + Nb + Ce + Y, (b) La/Sm versus La 2 2 ore formation (after Whalen et al., 1987), and (c) (La/Yb)N versus dEu. A = A-type granitoids; FG = I-type granitoids formed by differentiation; OGT = M/I/S-type granitoids formed without differentiation. We have used hornblende and biotite thermobarometry to estimate the temperature and pressure crystallization conditions of the Tongshan intrusion. The total Al content of hornblende (AlIV +- Tang et al., 1998) have shown that the Tongshan intrusion has ini- AlVI) can be used to quantify the crystallization pressure. The fol- 87 86 tial Sr/ Sr ratios of 0.7067–0.7076, which also requires a contri- lowing equation proposed by Johnson and Rutherford (1989) was bution from continental crust to mantle-derived magmas. used to calculate the crystallization pressure and depth (Table 3), The chemistry of hornblende and biotite can be used, to some with the crystallization depth estimated from a pressure–depth extent, to distinguish magma sources. Almost all the hornblende relationship of 1 kbar 3.3 km: data fall in the crust–mantle, mixed–source field in a plot of TiO2 T versus Al2O3 (Fig. 11a). Similarly, most biotite compositions lie in PðkbarÞ¼3:46 þ 4:23 Alð0:5 kbarÞ the crust–mantle, mixed–source field in a plot of RFeO/(RFeO + M- where TAl is the total Al content in the hornblende structure calcu- gO) versus MgO (Fig. 11b). This implies that both hornblende and lated on the basis of 23 oxygen atoms. biotite in the Tongshan intrusion are the products of crust–mantle, The hornblende–plagioclase geothermometer proposed by mixed–source magmatic crystallization, which is consistent with Blundy and Holland (1990) was used to determine the crystalliza- the trace element and Sr isotopic results. tion temperature of hornblende. Temperatures were calculated In summary, rocks of the Tongshan intrusion appear to be with the following equation (Table 3): crust–mantle-derived and mixed–source granitoids. The quartz diorite porphyry, quartz monzonite porphyry, and granodiorite 0:677P 48:98 þ Y Si 4 Plag T ¼ and K ¼ X porphyry are intermediate to acid intrusive rocks generated by 0:0429 0:008314 ln K 8 Si Ab Z.-Y. Zhang et al. / Journal of Asian Earth Sciences 79 (2014) 792–809 805 where Si is the atomic number per unit of hornblende, P is pressure lithounit layers. From the surface downward, these layers are the Plag in kbar, T is the absolute temperature in K, and XAb is the Ab value Mesozoic–Cenozoic continental sedimentary rock series (0– –2 of plagioclase (10 ). When XAb > 0.5, Y = 0 and when XAb < 0.5, 4 km), Mesozoic–Cenozoic marine sedimentary rock series (4– 2 Y = –0.806 + 25.5 (1 – XAb) . 8 km), Mesoproterozoic–Neoproterozoic low-grade metamorphic The hornblende crystallization pressures and temperatures of series (8–12 km), and Archean–Paleoproterozoic high-grade meta- rocks from the Tongshan intrusion are summarized in Table 6. morphic series (12–18 km). Zhou et al. (1993) and Du et al. (2004) For the quartz diorite porphyry, pressures fall into two ranges of considered that in the Anhui region magma chambers existed in 0.38–0.50 kbar and 1.55–1.62 kbar, corresponding to the depths of 1.24–1.63 km and 5.11–5.36 km, respectively. For these two pressure ranges, the crystallization temperatures are 671 °C and 705–755 °C. For the quartz monzonite porphyry, the crystallization pressures are mainly concentrated in the range 1.87–2.71 kbar (6.18–8.95 km), and crystallization temperatures vary from 707 to 768 °C. For the granodiorite porphyry, the crystallization pressures mostly range from 2.14 to 2.89 kbar (7.06–9.53 km), and the crystallization temperatures vary from 728 to 788 °C. In general, an increase in hornblende crystallization temperature and pressure (and depth) characterizes the sequence: quartz diorite porphyry ? quartz monzonite porphyry ? granodiorite porphyry. Previous studies have shown that the total aluminum content of biotite in granites corresponds with crystallization pressure (Etsuo et al., 2007). The following equation was used to estimate the biotite crystallization pressure (Table 2): PðkbarÞ¼3:03 TAl 6:53ð0:33Þ where TAl is the total aluminum content of biotite calculated on the basis of 22 oxygen atoms. The crystallization pressures of biotite in the Tongshan intrusion are also summarized in Table 6. For the quartz diorite porphyry, the crystallization pressures mainly range from 0.48 to 0.61 kbar, corresponding to depths of 1.57–2.02 km. For the quartz monzonite porphyry, the pressures range from 0.62 to 0.88 kbar (2.05–2.91 km). For the granodiorite porphyry, the pressures are mainly concentrated in the range 0.32–0.68 kbar (1.07–2.24 km). In general, an increasing trend in biotite crystallization pressure (and depth) characterizes the sequence: quartz diorite porphyry ? quartz monzonite porphyry. The biotite crystallization pressures of the granodiorite porphyry vary over a larger range than for the other two lithologies. Biotite chemistry shows that Si in the Si–O framework was only replaced by AlVI, and that Ti did not participate in this substitution (Table 2), which indicates that the biotite formed in a high-temperature environment (Deer et al., 1966). A Ti versus Mg/(Mg + Fe) temperature diagram was used to estimate the crystallization temperature of biotite (Fig. 12a). From this figure it is evident that the biotite crystallization temperatures were 750–770 °C, 765–775 °C, and 740–765 °C for the quartz diorite porphyry, quartz monzonite porphyry, and granodiorite porphyry, respectively. Tang et al. (1998) showed that the depth range of the upper Fig. 12. (a) Plot of Ti versus Mg/(Mg + Fe) for biotite (after Henry et al., 2005). (b) crust in the Anhui area along the MLYRB mainly comprises four Ternary Fe3+–Fe2+–Mg plot for biotite (after Wones and Eugeter, 1965).

Table 6 The ranges of pressures and temperatures of hornblendes and biotites during crystallization.

Mineral Lithology Pressure (kbar) Depth (km) Number Temperature (°C) Hornblende Quartz diorite porphyry 0.38–0.50 1.24–1.63 2 671 1.55–1.62 5.11–5.36 2 705–755 Quartz monzonite porphyry 1.17 3.85 1 707–768 1.87–2.71 6.18–8.95 3 3.10 10.25 1 Granodiorite porphyry 2.14–2.89 7.06–9.53 3 728–788 Biotite Quartz diorite porphyry 0.06 0.19 1 750–770 0.48–0.61 1.57–2.02 4 Quartz monzonite porphyry 0.62–0.88 2.05–2.91 5 765–775 735 (individual) Granodiorite porphyry 0.32–0.68 1.07–2.24 4 740–765 1.08 3.56 1 806 Z.-Y. Zhang et al. / Journal of Asian Earth Sciences 79 (2014) 792–809 the lower crust (24–29 km), mid-upper crust (9–15 km), and shal- REE (<15 lg/g). In a plot of Sr/Y versus Y (Fig. 13a), the three gran- low upper crust (4–6 km), and that the final emplacement depth of itoid types mainly fall in the adakite field. We also plotted our geo- magmas was at depths of 1.0–2.6 km. Mineral thermobarometry chemical data on diagrams of Nb versus Y (Fig. 13b) and Ta versus indicates that hornblende in the quartz diorite porphyry began to Yb (Fig. 13c). Data for all our samples fall in the volcanic arc granite crystallize in a shallow magma chamber that intruded the marine (VAG) and syn-collision granite (Syn-COLG) fields, which indicates sediments, and continued to crystallize after the magma ascended that the granitoids were generated in an arc setting. Furthermore, into the continental sediments. However, biotite only formed our zircon emplacement age for the quartz monzonite porphyry is mainly at very shallow levels when the magmas had ascended into 145.1 ± 1.2 Ma, which temporally coincides with the compres- the continental sedimentary rocks (Table 6). Hornblende in the sional to extensional transition in the Yangtze River region. In sum- quartz monzonite porphyry began to crystallize in a shallow mag- mary, integration of the geology of Tongshan region, together with ma chamber within the low-grade metamorphic layer, but most hornblende crystallization occurred when the magma ascended into the marine sedimentary rock layer and continued at shallower depths in the continental sedimentary rocks. Biotite in the quartz monzonite porphyry crystallized in the continental sedimentary rocks. Hornblende in the granodiorite porphyry began to crystallize in the layer of low-grade metamorphic rocks and continued to crystallize upon ascent into the marine sedimentary rocks, whereas biotite crystallized entirely in the continental sedimentary rocks. The co-existence of magnesio-biotite and accessory minerals such as primary magnetite and titanite in the Tongshan intrusion indicate that the magmas had a high oxygen fugacity. The chemical compositions of biotite are plotted in a Fe3+–Fe2+–Mg diagram (Wones and Eugeter, 1965), and all the data fall between the Ni–

NiO and Fe2O3–Fe3O4 buffer lines (Fig. 12b). Biotite in magmatic rocks from the Tongguanshan (Xu et al., 2004) and Wushan (Jiang et al., 2008; Dong et al., 2011) areas of the MLYRB also indicate a high oxygen fugacity for these magmas. Previous studies have demonstrated that high oxygen fugacity, mantle-derived magmas are favorable for the inclusion of ore-forming elements in the magma (Silltoe, 1997). Moreover, the formation of most porphyry– skarn copper deposits worldwide is closely related to intermediate to acid magmas with high oxygen fugacities (Meinert et al., 2005). Oxygen fugacity not only affects the melt sulfur content, but also fluid–melt differentiation, metal content of the produced skarns (Simon et al., 2003), and mineral composition and stability (Einau- di et al., 2003). The Tongshan magmas had high oxygen fugacities, which prevented incorporation of ore-forming Cu into silicate minerals during early stages of crystallization and enhanced incorporation of Cu into the later magmatic fluid phase (Li et al., 2008). Subsequently, fluid–rock interaction took place between these magmatic fluids and carbonate country rocks to form Cu-bearing skarns, as a part of the retrograde alteration stage (Zhang et al., 2010).

5.4. Tectonic implications

Mesozoic magmas with varying geochemical characteristics characterize the MLYRB, and the formation of these magmas was closely related to the regional strike-slip events along East Asia subsequent to the Triassic collision between the North China and Yangtze blocks (Tao et al., 1998; Qi et al., 2000). Magmas with different aluminum and alkali contents were produced during the tectonic transition at ca. 145–125 Ma and also during subsequent faulting at ca. 125–105 Ma (Du et al., 2007). Also critical was the onset of subduction of the paleo-Pacific plate beneath the Asian blocks at ca. 165 ± 5 Ma to 145 Ma, which has been shown to have been closely related to large-scale magmatism (Wu et al., 1982, 2008; Deng et al., 1992; Isozaki, 1997; Zhou and Li, 2000; Wang et al., 2004b, 2011; Mao et al., 2006, 2011; Ling et al., 2009; Li et al., 2009b). Negative Nb–Ta anomalies characterize all the rocks of the Tongshan intrusion, indicating that magmatism was subduc- Fig. 13. (a) Sr/Y versus Y, (b) Nb versus Y, and (c) Ta versus Yb discriminant plots used to identify the potential tectonic setting in which the Tongshan intrusion was tion-related (Sajona et al., 1996). The rocks have some adakitic emplaced (after Pearce et al., 1984; Defant and Drummond, 1990). WPG = within characteristics, such as high silica (SiO2 > 60 wt.%), alumina (Al2- plate granites; VAG = volcanic arc granites; syn-COLG = syn-collision granites; O3 > 14 wt.%), and Sr (Sr > 516 lg/g), and are also depleted in heavy ORG = oceanic ridge granites. Z.-Y. Zhang et al. / Journal of Asian Earth Sciences 79 (2014) 792–809 807 our geochronology and geochemical results for the Tongshan intru- Chen, J.-F., Li, X.-M., Zhou, T.-X., Foland, K.A., 1991. 40Ar–39Ar dating for the Yueshan sion, leads us to propose that this was arc magmatism related to diorite, Anhui Province and the estimated formation time of the associated ore deposit. Geoscience 5 (1), 90–99 (in Chinese with English abstract). subduction of oceanic crust in a continental margin setting. Chen, J.-F., Zhou, T.-X., Li, X.-M., Foland, K.A., Huang, C.-Y., Lu, W., 1993. The Sr and Nd isotope constraints of neutral and acid intrusive rocks of Yanshan Period, South of Anhui Province. Geochemica 3, 261–268 (in Chinese with English 6. Conclusions abstract). Chen, J.-F., Xie, Z., Zhang, X., Zhou, T.-X., 2001. Crustal evolution in Anhui: Nd and Sr isotopic evidence. Anhui Geology 11 (2), 123–130 (in Chinese with English (1) The Tongshan intrusion mainly comprises rocks that are abstract). quartz diorite porphyry, quartz monzonite porphyry, and Chen, J.-F., Yu, G., Yang, G., Yang, S.-H., 2005. A geochronological framework of late Mesozoic magmatism and metallogenesis in the lower Yangtze valley, Anhui granodiorite porphyry. Plagioclase in these rocks is primarily province. Anhui Geology 15 (3), 161–170 (in Chinese with English abstract). andesine–oligoclase (An = 18.0–42.9), whereas biotite is Chen, Y.-J., Chen, H.-Y., Zaw, K., Pirajno, F., Zhang, Z.-J., 2004. The geodynamic magnesio-biotite and hornblende is Mg-rich calcic setting of large-scale metallogenesis in mainland China, exemplified by skarn type gold deposits. Earth Science Frontiers 11 (1), 57–72 (in Chinese with hornblende. English abstract). (2) Hornblende and biotite thermobarometry constrain the Clements, J.D., Wall, V.J., 1984. Origin and evolution of a peraluminous silicic temperature and pressure conditions for the formation of ignimbrite suite. The Violet Town Volcanics. Contributions to Mineralogy and Petrology 88, 354–371. the quartz diorite porphyry as 693–755 °C and 0.82– Deer, W.A., Howie, R.A., Zussman, J., 1966. An Introduction to the Rock-Forming 1.01 kbar (depth = 2.71–3.34 km), respectively. Temperature Minerals. Longman Group UK Ltd., UK. and pressure crystallization conditions of the quartz monzo- Defant, M.J., Drummond, M.S., 1990. Derivation of some modern arc magmas by nite porphyry were 737–745 °C and 1.12–2.19 kbar melting of young subducted lithosphere. Nature 347, 662–665. Deng, J.-F., Ye, D.-L., Zhao, H.-L., 1992. Volcanism Deep Internal Progresses Basin (depth = 3.69–7.24 km), respectively, and for the granodio- Formation in the Lower Reaches of the Yangtze River. China University of rite porphyry were 717–750 °C and 1.12–2.19 kbar Geosciences Press, Wuhan, pp. 1–184 (in Chinese with English abstract). (depth = 3.69–7.24 km). Ding, X., Jiang, S.-Y., Ni, P., Gu, L.-X., Jiang, Y.-H., 2005. Zircon SIMS U–Pb geochronology of host granitoids in Wushan and Yongping copper deposits, (3) The quartz monzonite porphyry yielded a zircon U–Pb age of Jiangxi Province. Geological Journal of China Universities 11 (3), 383–389 (in 145.1 ± 1.2 Ma, which corresponds to middle Yanshanian. All Chinese with English abstract). lithologies of the Tongshan intrusion are high-K, calc-alka- Ding, X., Jiang, S.-Y., Zhao, K.-D., Nakamura, E., Kobayashi, K., Ni, P., Gu, L.-X., Jiang, Y.-H., 2006. In situ U–Pb SIMS dating and trace element (EPMA) composition of line rocks that are enriched in silica, alkalis, light REEs, and zircon from a granodiorite porphyry in the Wushan copper deposit, China. large ion lithophile elements, and depleted in heavy REEs Contribution to Mineralogy and Petrology 86, 29–44. and high field strength elements. Magmas of the Tongshan Dong, Q., Du, Y.-S., Cao, Y., Pang, Z.-S., Song, L.-X., Zhen, Z., 2011. Compositional characteristics of biotites in Wushan granodiorite, Jiangxi Province: intrusion are mixed-source granitoids with mantle and crus- implications for petrogenesis and mineralization. Journal of Mineralogy and tal contributions, which formed from multiple batches of Petrology 31 (2), 1–6 (in Chinese with English abstract). ascending magma that were generated by mixing of basaltic Du, J.-G., Dai, S.-Q., Mo, X.-X., Deng, J.-F., Xu, W., 2003. Petrogenic and metallogenic settings of area along Yangtze River in Yanshanian, Anhui province. Earth magma from enriched lithospheric mantle with lower crus- Science Frontiers 10 (4), 551–560 (in Chinese with English abstract). tal material. The intrusion was emplaced in an arc setting, Du, Y.-S., Qin, X.-L., Tian, S.-H., 2004. Mesozoic magmatic to hydrothermal process and was closely related to the subduction of oceanic crust. in the Tongguanshan ore field, Tongling, Anhui province, China: Evidence from xenoliths and their hosts. Acta Petrologica Sinica 20 (2), 339–350 (in Chinese with English abstract). Du, Y.-S., Li, S.-T., Cao, Y., Qin, X.-L., Lou, Y.-E., 2007. UAFC: related origin of the Late Jurassic to Early Cretaceous intrusions in the Tongguanshan ore field, Tongling, Acknowledgments Anhui province, East China. Geoscience 21 (1), 71–77 (in Chinese with English abstract). Einaudi, M.T., Hedenquist, J.W., Inan, E., 2003. Sulfidation state of hydrothermal This study was financially supported by the National Natural fluids. The porphyry-epithermal transition and beyond. Society of Economic Science Foundation of China (Grants: 40672045), the China Geo- Geologists Special Publication 10, 317–391. logical Survey (Grants: 20089938), the Ministry of Education of Etsuo, U., Sho, E., Mitsutoshi, M., 2007. Relationship between solidification depth of granitic rocks and formation of hydrothermal ore deposits. Resource Geology 57 China (No. 308006), and the 111 Project (No. B07011). We thank (1), 47–56. senior engineers Yong Wan, Pinjie Li, and Gang Xu in the Geology Foster, M.D., 1960. Interpretation of composition of trioctahedral micas. US Branch of Tongshan copper mine, and thank Dr. Dapeng Li, Pengfei Geological Survey Professional Paper 354B, 1–49. Jia, Yucui Dong, and Xianglian Li for their support during fieldwork. Hanchar, J.M., Miller, C.F., 1993. Zircon zonation patterns as revealed by cathodoluminescence and backscattered electron images: Implications for We are indebted to He Rong for analytical assistance on the elec- interpretation of complex crustal histories. Chemical Geology 110, 1–13. tron microprobe, Hui Zhou, Yuruo Shi, Jiajun Wan for U–Pb zircon Henry, D.J., Guidotti, C.V., Thomoson, J.A., 2005. The Tisaturation surface for low-to- SHRIMP dating, and Bin Yang, Libing Gu, Fang Ma, as well as Hebei medium pressure metapelitic biotites: implications for geothermometry and Ti substitution mechanisms. American Mineralogist 90, 316–328. Areal Geology Mineral Survey Institute. All of these colleagues sup- Hu, J.-P., Jiang, S.-Y., 2010. Zircon U–Pb dating and Hf isotopic compositions of plied valuable assistance for obtaining the experimental data. We porphyrites from the Ningwu basin and their geological implications. are deeply grateful to Professor Jingwen Mao and three anonymous Geological Journal of China Universities 16 (3), 294–308 (in Chinese with English abstract). reviewers for their constructive suggestions. Isozaki, Y., 1997. Jurassic accretion tectonics of Japan. The Island Arc 6 (1), 25–51. Jiang, C.-Y., An, S.-Y., 1984. On chemical characteristics of calcic amphiboles from igneous rocks and their petrogenesis significance. Journal of Mineralogy and References Petrology 3, 1–9 (in Chinese with English abstract). Jiang, S.-Y., Li, L., Zhu, B., Ding, X., Jiang, Y.-H., Gu, L.-X., Ni, P., 2008. Geochemical and Sr–Nd–Hf isotopic compositions of granodiorite from the Blundy, J.D., Holland, T.J.B., 1990. Calcic amphibole equilibria and a new amphibole– Wushan copper deposit, Jiangxi Province and their implications for plagioclase geothermometer. Contributions to Mineralogy and Petrology 104, petrogenesis. Acta Petrologica Sinica 24 (8), 1679–1690 (in Chinese with 208–224. English abstract). Boynton, W.V., 1984. Geochemistry of the rare earth elements: meteorite studies. Johnson, M.C., Rutherford, M.J., 1989. Experimental calibration of the aluminium- In: Henderson, P. (Ed.), Rare Earth Element Chemistry. Elsevier, Amsterdam, pp. in-hornblende geobarometer with application to Long Valley caldera 63–114. (California) volcanic rocks. Geology 17 (9), 837–841. Cao, Y., Du, Y.-S., Pang, Z.-S., Li, S.-T., Zhang, J., Zhang, Z.-C., 2009. Underplating and Leake, B.E., Woolley, A.R., Arps, C.E.S., 1997. Nomenclature of amphiboles report of assimilation-fractional crystallization of Mesozoic intrusions in the Tongling the subcommittee on amphiboles of the international mineralogical association, area, Anhui Province, East China: evidence from xenoliths and host plutons. commission on new mineral and mineral names. American Mineralogist 82, International Geology Review 51 (6), 542–555. 1019–1037. Chen, J.-F., Jiang, B.-M., 1999. Nd, Sr, Pb isotope tracer and continent crust evolution Li, X.-H., 2000. Cretaceous magmatism and lithospheric extension in Southeast in southeastern China. Geochemica 28 (2), 127–140 (in Chinese with English China. Journal of Asian Earth Sciences 18, 293–305. abstract). 808 Z.-Y. Zhang et al. / Journal of Asian Earth Sciences 79 (2014) 792–809

Li, L., Jiang, S.-Y., 2009. Petrogenesis and geochemistry of the Dengjiashan Silltoe, R.H., 1997. Characteristics and controls of the largest porphyry copper–gold porphyritic granodiorite, Jiujiang–Ruichang metallogenic district of the and epithermal gold deposits in the circum-Pacific region. Australian Journal of middle-lower reaches of the Yangtze River. Acta Petrologica Sinica 25 (11), Earth Sciences 44, 373–388. 2877–2888 (in Chinese with English abstract). Simon, A.C., Pettke, T., Candela, P.A., Piccoli, P.M., Heinrich, C.A., 2003. Experimental Li, L.-P., Shao, J.-L., 1994. Geochemical characteristics of Tongshan copper ore determination of Au solubility in rhyolite melt and magnetite constrains on deposit, Guichi, Anhui. Geology and Prospecting 3, 9–13 (in Chinese with magmatic Au budgets. American Mineralogist 88, 1644–1651. English abstract). Stacey, J.S., Kramers, J.D., 1975. Approximation of terrestrial lead isotope evolution Li, J.-W., Zhao, X.-F., Zhou, M.-F., Ma, C.-Q., Zorano, S.D.S., Vasconcelos, P., 2008. by a two-stage model. Earth and Planetary Science Letters 26, 207–221. Origin of the Tongshanku porphyry-skarn Cu–Mo deposit, eastern Yangtze Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematics of oceanic craton, Eastern China Geochronological, geochemical, and Sr–Nd–Hf isotopic basalts: implication for mantle composition and processes. In: Sauders, A.D., constraints. Mineral Deposita 43, 315–336. Norry, M.J. (Eds.), Magmatism in the Ocean Basin, Geol. Soc. Spec. Pub. 42, pp. Li, H.-Q., Chen, F.-W., Mei, Y.-P., 2009a. SHRIMP U–Pb zircon dating of the 313–345. mineralization intrusion from Jiguanzui orefield in eastern Hubei province Sun, Y.-L., Zhang, L.-M., Zhang, H.-Z., Liu, Q., 2008. The practice and inspiration of and its geological significance. Geotectonicaet Metallogenia 33 (3), 411–417 (in deep ore-prospecting of Tongshan Cu deposit, Chizhou. Geology of Yunnan 27 Chinese with English abstract). (1), 40–45 (in Chinese with English abstract). Li, J.-W., Zhao, X.-F., Zhou, M.-F., Ma, C.-Q., Souza, Z.S., Vasconcelos, P.M., Deng, X.-D., Tang, Y.-C., Wu, Y.-C., Chu, G.-Z., Xing, F.-M., Wang, Y.-M., Cao, F.-Y., Chang, Y.-F., Zhao, Y.-X., Wu, G., 2009b. Late Mesozoic magmatism from Daye region, Eastern 1998. Geology of Copper–Gold Polymetallic Deposits in Anhui Province along China: U–Pb ages, petrogenesis and geodynamic implications. Contributions to the Yangtze River. Geological Publishing House, Beijing, pp. 76–80 (in Chinese). Mineralogy and Petrology 157, 383–409. Tao, K.-Y., Mao, J.-R., Yang, Z.-L., Zhao, Y., Xing, G.-F., Xue, H.-M., 1998. Mesozonic Ling, M.-X., Wang, F.-Y., Ding, X., Hu, Y.-H., Zartman, R.E., Xiong, X.-L., Sun, W.D., petro-tectonic associations and records of the geodynamic processes in 2009. Cretaceous ridge subduction along the Lower Yangtze River belt, Eastern southeast China. Earth Science Frontiers 5 (4), 183–192 (in Chinese with China. Economic Geology 104, 303–321. English abstract). Liu, Z.-S., Wang, J.-M., 1994. Geology and Geochemistry of Granites in Southern Vavra, G., Gebauer, D., Schmid, R., 1996. Multiple zircon growth and Tibetan Plateau. Sichuan Science and Technology Press, Chengdu, pp. 1–133 (in recrystallization during polyphase Late Carboniferous to Triassic Chinese). metamorphism in granulite of the Ivrea Zone (South Alps): an ion microprobe Liu, Y.-Y., Ma, C.-Q., Zhang, C., She, Z.-B., Zhang, J.-Y., 2009. Petrogenesis of Yueshan (SHRIMP) study. Contributions to Mineralogy and Petrology 122, 337–358.

pluton: zircon U–Pb dating and Hf isotope evidence. Geological Science and Wang, Y., 2003. Ore-controlling character of F1 fracture zone of Tongshan copper Technology Information 28 (5), 22–30 (in Chinese with English abstract). deposit. Mineral Resources and Geology 17 (4), 530–532 (in Chinese with Lou, Y.-E., Du, Y.-S., 2006. Characteristics and zircon SHRIMP U–Pb ages of the English abstract). Mesozoic intrusive rocks in Fanchang, Anhui province. Geochemica 35 (4), 359– Wang, Y., Deng, J.-F., Ji, G.-Y., 2004a. A perspective on the geotectonic setting of 366 (in Chinese with English abstract). Early Cretaceous adakite-like rocks in the lower reaches of Yangtze River and its Lü, J.-W., 2000. Characteristics of rock in Tongshan. Mineral Resources and Geology significance for copper–gold mineralization. Acta Petrologica Sinica 20 (2), 297– 14 (3), 172–174 (in Chinese with English abstract). 311 (in Chinese with English abstract). Lu, J.-J., Guo, W.-M., Chen, W.-F., Jiang, S.-Y., Li, J., Xu, Z.-W., 2008. A metallogenic Wang, Y.-B., Liu, D.-Y., Meng, Y.-F., Zeng, P.-S., Yang, Z.-S., Tian, S.-H., 2004b. SHRIMP model for the Dongguashan Cu–Au deposit of Tongling, Anhui province. Acta U–Pb geochronology of the Xinqiao Cu–S–Fe–Au deposit in the Tongling ore Petrologica Sinica 24 (8), 1857–1864 (in Chinese with English abstract). district, Anhui. Chinese Geology 25 (2), 87–91 (in Chinese with English Ludwig, K.R., 2001. Squid 1.02: a user’s manual. Berkeley Geochronology Centre. abstract). Special Publication 2, 1–19. Wang, Q.-F., Deng, J., Huang, D.-H., Xiao, C.-H., Yang, L.-Q., Wang, Y.-R., 2011. Ludwig, K.R., 2003. User’s manual for Isoplot 3.00, a geochronological toolkit for Deformation model for the Tongling ore cluster region, east-central China. Microsoft excel. Berkeley, California: Berkeley Geochronology Center. Special International Geology Review 53 (5–6), 562–579. Publication 4, 70. Whalen, J.B., Chappell, B.W., 1988. Opaque mineralogy and mafic mineral chemistry Ma, Z.-D., Shan, G.-X., 1997. Geological–geochemical studies of the formation of I- and S-type granites of the Lachlan fold belt, southeast Australia. American mechanism of ‘‘integral whole of multiplaces’’ large and superlarge copper Mineralogist 73, 281–296. deposits in the middle and lower reaches of the Yangtze river. Mineral Deposits Whalen, J.B., Currie, K.I., Chappell, B.W., 1987. A-type granites: geochemical 16 (3), 225–234 (in Chinese with English abstract). characteristics, discrimination and petrogenesis. Contributions to Mineralogy Mao, J.-W., Wang, Y.-T., Lehmann, B., Yu, J.-J., Du, A.-D., Mei, Y.-X., Li, Y.-F., Zang, W.- and Petrology 95 (4), 407–419. S., Stein, H.J., Zhou, T.-F., 2006. Molybdenite Re–Os and albite 40Ar/39Ar dating Williams, I.S., 1998. U–Th–Pb geochromology by ion microprobe. In: McKibben, of Cu–Au–Mo and magnetite porphyry systems in the Yangtze River valley and M.A., Shanks, W.C., Ridley, W.I. (Eds.), Applications of Microanalytical metallogenic implications. Ore Geology Reviews 29 (3–4), 307–324. Techniques to Understanding Mineralizing Processes. Reviews of Economic Mao, J.-W., Shao, Y.-J., Xie, G.-Q., Zhang, J.-D., Chen, Y.-C., 2009. Mineral deposit Geology 7, pp. 1–35. modle for porphyry-skarn polymetallic copper deposits in Tongling ore dense Wones, D.P., Eugeter, H.P., 1965. Stability of biotite: experiment, theory, and district of middle-lower Yangtze valley metallogenic belt. Mineral deposit 28 application. The American Mineralogist 50, 1228–1272. (2), 109–119 (in Chinese with English abstract). Wu, L.-R., Qi, J.-Y., Wang, T.-D., Zhang, X.-Q., Xu, Y.-S., 1982. Mesozoic volcanic rocks Mao, J.-W., Xie, G.-Q., Duan, C., Pirajno, F., Ishiyama, D., Chen, Y.-C., 2011. A tectono- in east China. Acta Geologica Sinica 56 (3), 223–234 (in Chinese). genetic model for porphyry-skarn-stratabound Cu–Au–Mo–Fe and magnetite– Wu, G.-G., Zhang, D., Di, Y.-J., Zang, W.-S., Zhang, X.-X., Song, B., Zhang, Z.-Y., 2008. apatite deposits along the Middle–Lower Yangtze River Valley, Eastern China. U–Pb SHRIMP dating of zircons of the Tongling pluton and deep dynamics Ore Geology Reviews 43, 294–314. background. Science in China (Series D) 38 (5), 630–645 (in Chinese). Mei, Y.-X., Mao, J.-W., Li, J.-W., Du, A.-D., 2005. Re–Os dating of molybdenite from Wu, F.-Y., Ji, W.-Q., Sun, D.-H., Yang, Y.-H., Li, X.-H., 2012. Zircon U–Pb stratiform skarn orebodies in the Datuanshan copper deposit, Tongling, Anhui geochronology and Hf isotopic compositions of the Mesozoic granites in province, and its geological significance. Acta Geoscientica Sinica 26 (4), 327– southern Anhui Province, China. Lithos 150, 6–25. 331 (in Chinese with English abstract). Xie, G.-Q., Mao, J.-W., Li, R.-L., Zhou, S.-D., Ye, H.-S., Yan, Q.-R., Zhang, Z.-S., 2006. Meinert, L.D., Dipple, G.M., Nicolescu, S., 2005. World skarn deposits. Economic SHRIMP dating of Dasi formation volcanic rocks in southeastern Hubei province Geology 100th Anniversary Volume, 299–336. from Middle and Lower Reaches of the Yangtze River area and its significance. Pan, Y.-M., Dong, P., 1999. The lower Changjing (Yangzi/Yangtze River) metallogenic Chinese Science Bulletin 51 (19), 2283–2291 (in Chinese). belt, east central China: Intrusion- and wall rock-hosted Cu–Fe–Au, Mo, Zn, Pb, Xie, G.-Q., Mao, J.-W., Zhao, H.-J., 2011. Zircon U–Pb geochronological and Hf Ag deposits. Ore Geology Reviews 15 (4), 177–241. isotopic constraints on petrogenesis of Late Mesozoic intrusions in the Pan, Z.-L., Zhao, A.-X., Pan, T.-H., 1994. Crystallography and Mineralogy. Geological southeast Hubei Province, Middle-Lower Yangtze River belt (MLYRB), East Publishing House, Beijing, pp. 191–196 (in Chinese). China. Lithos 125 (1–2), 693–710. Pearce, J.A., Harris, N.B.W., Tindle, A.G., 1984. Trace element discrimination Xie, G.-Q., Mao, J.-W., Zhao, H.-J., Duan, C., Yao, L., 2012a. Zircon U–Pb and diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology phlogopite 40Ar–39Ar age of the Chengchao and Jinshandian skarn Fe deposits, 25, 956–983. southeast Hubei Province, Middle-Lower Yangtze River Valley metallogenic Qi, J.-Z., Liu, H.-Y., Jiang, Y.-H., 2000. Yanshanian subduction and strike-sliping belt, China. Mineralium Deposita 47, 633–652. regime of East China, and its control of ore localization. Volcanology and Xie, J.-C., Yang, X.-Y., Sun, W.-D., Du, J.-G., 2012b. Early Cretaceous dioritic rocks in Mineral Resources 21 (4), 244–266 (in Chinese with English abstract). the Tongling region, eastern China: implications for the tectonic settings. Lithos Rickwood, P.C., 1989. Boundary lines within petrologic diagrams which use oxides 150, 49–61. of major and minor elements. Lithos 22, 247–263. Xu, J.-F., Wang, Q., Xu, Y.-G., Zhao, Z.-H., Xiong, X.-L., 2001. Geochemistry of Robert, P.R., Long, X., Nobu, S., 2002. Experimental constrains on the origin of Anjishan intermediate-acid intrusive rocks in Ningzhen area: constraint to potassium-rich adakites in eastern China. Acta Petrologica Sinica 18 (3), 293– origin of the magma with HREE and Y depletion. Acta Petrologica Sinica 17 (4), 302. 576–584 (in Chinese with English abstract). Sajona, F.G., Maury, R.C., Bellon, H., Cotton, J., Defant, M., 1996. High field strength Xu, X.-S., Fan, Q.-C., O’Reilly, S.Y., Jiang, S.-Y., Griffin, W.L., Wang, R.-C., Qiu, J.-S., element enrichment of Pliocene–Pleistocene island arc basalts, Zamboanga 2004. U–Pb Dating of zircons and petrogenic implications for Tongguanshan Peninsula, western Mindanao (Philippines). Journal of Petrology 37, 693–726. quartz diorite and its enclaves, Anhui Province. Chinese Science Bulletin 49 (19), Shao, Y.-J., Zheng, M.-H., Liu, W.-H., Li, P.-J., Liu, Z.-F., Liu, Q.-Q., 2009. The key ore- 2073–2082. controlling factor and mineralization positioning study of Tongshan copper Xu, Y.-M., Jiang, S.-Y., Zhu, Z.-Y., Zhou, W., Kong, F.-B., Sun, M.-Z., 2012. deposit in Anhui Province. Acta Mineralogica Sinica Supply, 555–557 (in Geochronology, geochemistry and mineralization of the quartz diorite– Chinese). porphyrite and granodiorite porphyry in the Shanshangwan area of the Jiurui Z.-Y. Zhang et al. / Journal of Asian Earth Sciences 79 (2014) 792–809 809

ore district, Jiangxi Province. Acta Petrologica Sinica 28 (10), 3306–3324 (in province: constraints from U–Pb SHRIMP dating of zircons and structural Chinese with English abstract). deformation. Earth Science 31 (6), 823–830 (in Chinese with English abstract). Xue, H.-M., Dong, S.-W., Ma, F., 2012. Zircon SHRIMP U–Pb ages of volcanic rocks in Zhang, L.-J., Zhou, T.-F., Fan, Y., Yuan, F., 2008. SHRIMP U–Pb zircon dating of the Luzong basin, Middle and Lower Yangtze River Reaches: constraints on the Yueshan intrusion in Yueshan ore field, Anhui, and its significance. Acta model of late Mesozoic lithospheric thinning of the Eastern Yangtze craton. Acta Petrologica Sinica 24 (8), 1725–1732 (in Chinese with English abstract). Geologica Sinica 86 (10), 1569–1583 (in Chinese with English abstract). Zhang, Z.-Y., Du, Y.-S., Zhang, J., Pang, Z.-S., Li, D.-P., Jia, P.-F., 2010. Alteration and Yan, J., Yu, Y.-F., Chen, J.-F., 2009a. Rb–Sr isotopic dating of volcanic rocks from the mineralization zoning in Tongshan skarn-type copper deposit in Guichi, Anhui Niangniangshan Formation in the Nanjing–Wuhu area and its geological Province, and its genesis. Mineral Deposits 29 (6), 999–1016 (in Chinese with implications. Geological Review 55 (1), 121–125 (in Chinese with English English abstract). abstract). Zhou, Z.-X., 1986. The origin of intrusive mass in Fengshandong, Huibei Province. Yan, J., Liu, H.-Q., Song, C.-Z., Xu, X.-S., An, Y.-J., Liu, J., Dai, L.-Q., 2009b. Zircon U–Pb Acta Petrologica Sinica 2 (1), 59–70 (in Chinese with English abstract). geochronology of volcanic rocks in Fanchang–Ningwu volcanic basin from Zhou, Y.-E., 1997. The characteristics of REEs in some geological bodies of the Middle and Lower Reaches of the Yangtze River and its geological significance. Tongshan copper ore deposit and their implications. Geology of Anhui 7 (2), 51– Chinese Science Bulletin 54 (12), 1716–1724 (in Chinese). 58 (in Chinese with English abstract). Yang, X.-N., Xu, Z.-W., Xu, X.-S., Ling, H.-F., Liu, S.-M., Zhang, J., Li, H.-Y., 2008. Zircon Zhou, S.-G., 2003. Matter source of the Tongshan deposit and its mineralization. U–Pb geochronology and its implication for the temperature of Yanshanian Mineral Resources and Geology 17 (5), 610–612 (in Chinese with English Magma in Tongling, Anhui province. Acta Geologica Sinica 82 (4), 510–516 (in abstract). Chinese with English abstract). Zhou, X.-M., Li, W.-X., 2000. Origin of Late Mesozoic igneous rocks in southeastern Yang, X.-N., Xu, Z.-W., Lu, X.-C., Jiang, S.-Y., Ling, H.-F., Liu, L.-G., Chen, D.-Y., 2011. China: Implications for lithosphere subduction and underplating of mafic Porphyry and skarn Au–Cu deposits in the Shizishan orefield, Tongling, East magmas. Tectonophysics 326 (3–4), 269–287. China: U–Pb dating and in-situ Hf isotope analysis of zircons and petrogenesis Zhou, X.-R., Wu, C.-L., Huang, X.-C., Zhang, C.-H., 1993. Characteristics of cognate of associated granitoids. Ore Geology Reviews 43 (1), 182–193. inclusions in intermediate-acid intrusive rocks of Tongling area and their Yu, C.-H., 2001. Study on the genesis of Tong shan copper ore deposit in Guichi. magmatic dynamics. Acta Petrologica et Mineralogica 12 (1), 20–31 (in Chinese Geology and Prospecting 37 (2), 12–16 (in Chinese with English abstract). with English abstract). Yu, C.-H., Yuan, X.-M., 1999a. The petrochemical and geochemical characteristics of Zhou, T.-F., Yuan, F., Yue, S.-C., 2003. 40Ar/39Ar fast neutron activation dating of the Tongshan intrusive, Guichi. Geology of Anhui 9 (3), 194–197 (in Chinese quartz from the Tongniujing Cu, Mo, Au vein-type hydrothermal deposit, Anhui. with English abstract). Geological Review 49 (2), 212–216 (in Chinese with English abstract). Yu, C.-H., Yuan, X.-M., 1999b. The relationship between mineralization and Zhou, T.-F., Song, M.-Y., Fan, Y., Yuan, F., Liu, J., Wu, M.-A., Qian, C.-C., Lu, S.-M., 2007. evolution of rock in Tongshan Quichi. Mineral Resources and Geology 13 (5), Chronology of the Bajiatan intrusions in the Luzong basin, Anhui, and its 274–278 (in Chinese with English abstract). significance. Acta Petrologica Sinica 23 (10), 583–591 (in Chinese with English Zeng, P.-S., Yang, Z.-S., Meng, Y.-F., Pei, R.-F., Wang, Y.-B., Wang, X.-C., Xu, W.-Y., abstract). Tian, S.-H., Yao, X.-D., 2004. Temporal–spatial configuration and mineralization Zhou, T.-F., Fan, Y., Yuan, F., 2008a. Advances on petrogensis and metallogeny study of Yanshanian magmatic fluid systems in Tongling ore concentration area, of the mineralization belt of the Middle and Lower Reaches of theYangtze River Anhui province. Mineral Deposits 23 (3), 298–308 (in Chinese with English area. Acta Petrologica Sinica 24 (8), 1665–1678 (in Chinese with English abstract). abstract). Zeng, J.-N., Tan, Y.-J., Guo, K.-Y., Chen, G.-G., Zeng, Y., 2010. Zircon U–Pb dating of Zhou, T.-F., Fan, Y., Yuan, F., Lu, S.-M., Shang, S.-G., David, C., Sebastien, M., Zhao, G.- ore-bearing magmatic rocks and its constraint on the formation time of the ore C., 2008b. Geochronology of the volcanic rocks in the Lu Zone (Lujiang– deposits in Luzong Basin, Anhui Province. Acta Geologica Sinica 84 (4), 466–478 Zongyang) basin and its significance. Science in China (Series D) 51 (10), 1470– (in Chinese with English abstract). 1482. Zhai, Y.-S., Yao, S.-Z., Lin, X.-D., Zhou, X.-N., Wan, T.-F., Jin, F.-Q., Zhou, Z.-G., 1992. Zhu, G., Liu, G.-S., Niu, M.-L., Song, C.-Z., Wang, D.-X., 2003. Transcurrent movement Fe–Cu–Au Metallogeny of the Middle-Lower Changjiang Region. Geological and genesis of the Tan-Lu fault zone. Regional Geology of China 22 (3), 200–207 Publishing House, Beijing, p. 235 (in Chinese). (in Chinese with English abstract). Zhang, D., Wu, G.-G., Di, Y.-J., Zang, W.-S., Shao, Y.-J., Yu, X.-Q., Zhang, X.-X., Wang, Q.-F., 2006. Emplacement dynamics of fenghuangshan pluton, Tongling, Anhui